Electric arc disrupter



March 29, 1932. P. J. BRANCHU 398519238 ELECTRIC ARC DISRUPTER FiledApril 29. 1929 Patented Mar. 29, 1932 PAUL JOSEPH BRANC HU, OF GRENOBLE,FRANCE ELECTRIC ARC DISRUITER Application filed April 29, 1929, SerialNo. 359,128, and in France Hay-10, 1928.

The present invention relates to devices adapted to blow the electricarcs in circuit breakers and its object is to provide an improved deviceefiectiveto so modify the mag- 5 netic flux blowing the are that thefield is reinforced in the regions most favorable for the good workingof the circuit breaker or switch.

The invention consists in placing within the field a conductor a, b,constituting a circuit closed on itself and comprising two 0ppositelywound windings in the shape of a figure 8 of different sizes. Variationsof the blowout field induce E. M. F. in each winding, but th E. M. F. ofthe larger loop will be larger as its linkage with the field flux isgreater, consequently a current will flow in the two loops. Thedirection of winding is such that this current reduces the flux due tothe blowout winding in the region of the upper or larger loop andincreases it in the region of the small loop near the contacts.

These properties can be, for example, utilized to reinforce the fieldblowing the are .at the moment of working of a switch.

In the drawings:

Fig. '1 is a section of an embodiment of the invention taken on the line1-1 of'Fig. 2;

Fig. 2 is an elevation at right angles to Fig. 3 is a detail elevationof a modified form of the coils' and showing one of the coils.

According to this latter embodiment p is the line traversed by the maincurrent and g is the blowing coil placed inseries in this line andcreating a magnetic field in a mag- I netic circuit 7.

1 In the air-gap of f are placed two contacts a, 0', the first 0 beingformed by the extremity of a movable arm q pivoting around an axis 9,the working of the movable arm 9 being secured in any way.

The blowing box is formed in the usual way by insulating walls d, e.

The invention consists in that a conductor a,bclosed in itself andforming the secondary winding of a transformer whose primary winding isconstituted by the blowing coil' g, is placed. in the field blowing thearc engenopening of the circuit breaken-will be dered between 0, 0'.This secondary conductor is situated outside of the blowing box and isseparated from the arc.

According to the embodiment represented in Figs. 1 and 2 this secondaryconductor as forms the figure 8 whose two loops a, b are thereforereversed, as to direction, and moreover are unequal in size, the greaterloop a surrounding the field in a' region removed from the point wherethe contacts 0,0 meet 60 or are to beseparated, the small loop 5 beingsituated in the region of these contacts 0, o; r The device serves to'distort the field between the pole pieces, strengthening the field inthe region of the initial arc and decreasing it above that point. i

If the current increases rapidly in-the coil 9 (because of ashort-circuit or for any other reason), the magnetic field tends equallyto augment. Owing to the increase of the flux across both loops a, b ofthe 8-1ike shaped conductor. electromotive forces are engendered in eachloop, tending according to the lawof Lenz to oppose themselves to thevariations of the flux. The great loop a trav- 7 ersed by a greater fluxthan the small loop I), has generated therein an electromotive forcegreater than the latter. These electromotive forces being each theopposite of the other, a current will be established in the sense of thegreater one, which current will pass into the small loop I) in adirection inverse to the direction of the electromotive forceengendered. It is obvious that the effect produced by this current withregard to 8 the fie d in the small loop b will act opposite- 1y to thelaw of Lenz, viz. will tend to reinforce the variations of the currentinstead of opposing itself to them. Consequently the field will bereinforced in the space enclosed by the small loop 6, thatis in theneighborhood of the contacts 0, c in the period of in-' crease of thecurrentin the coil g. Hence the roduced during the period of theincrease 0 the current, and the b owing field will be reinforced in theneighbourhood of the points 0, 0'. which fact is favorable to theworking of the circuit-breaker.

Fig. 3 represents an embodiment according to which the secondaryconductor comprises several loops (1, b of increasing dimensions.

In this manner it is possible to obtain a reinforced field especially inthe immediate neighbourhood of the contacts 0, a.

The invention is, of course, not limited to the embodiments shown anddescribed and extends to all kinds of disjunctors and circuit breakerswhose magnetic flux blowing the arc can be very favorably modified.

' What I claim is:

1. In an electric arc interrupter, a fixed contact and a movable contacttraversed by the circuit to be opened, a core, a blowout coil on thecore'in series with the circuit to be opened, whereby a magnetic fieldis created, and a second coil in short circuit disposed in the saidmagnetic field and having windings in the form of afigure 8 so as todeform the v blowout field. r

2. An interrupter as claimed in claim 1, in which the second coil inshort circuit is in the form of a figure 8 having two loops, unequal insize and the smaller of which is located in the region of the contactsto reinforce the magnetic field in the said region.

In witness whereof I affix my signature.

' PAUL JOSaEPI-I BRANCHU.

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